Enable partition_by config value for columns that are not lineages

[Taepper]

Currently, the database_config's field partition_by must refer to a lineage column. This could be generalized to allow all data types. The implementation effort should be marginal.

Yet, it is undecided whether we want to support that functionality.

Pro:
We can enable clearer and better to debug partitioning logic, which can be fine-tuned by a silo user.

Con:
While the code might not become more complicated, we still have a bigger surface for which we need testing